Process controller for balancing usage of tool sets

Abstract

A system monitors usage of a tool in a tool set and warns an operator and/or prevents usage of a tool chosen by an operator, subject to possible override by the operator, if permitted, in order to balance usage among tools of the tool set and verify operational conditions of tools of the tool set through usage. The system and method are entirely transparent to the operator and the operator is permitted full flexibility of tool choice unless tool usage becomes unbalanced. The system and method preferably limits usage based on length of consecutive usage and percentage of product processed by each tool. Use of new, modified or repaired tools is also prevented until the tool is certified for a particular process and defined to the system.

Description

1. Field of the InventionThe present invention generally relates to physical processes such as manufacturing processes for which tools are used and, more particularly, to operator-supervised automated processes for which a plurality of suitable tools may be concurrently available such as lithography or other semiconductor manufacturing processes.2. Description of the Prior ArtMany physical processes such as those used in manufacturing require the use of tools in order to accomplish the desired result. Often, the tools are specially designed and constructed or adapted for particular processes. Lithographic exposure tools and plasma reactor vessels (either of which may be of any one of many different designs, capacities, efficiencies and the like) are examples of expensive, special-purpose tools used for semiconductor manufacturing processes. However, it is to be understood that many other examples of physical processes and tools for performing them exist and may be of substantially g...

AI Technical Summary

Problems solved by technology

However, it is to be understood that many other examples of physical processes and tools for performing them exist and may be of substantially greater or lesser cost and complexity.

Whether the process or the tool is simple or highly complex, there is a tendency for the same tool to be repeatedly used to carry out a given process.

In critical manufacturing processes, such as those involved in semiconductor integrated circuit manufacture, however, such a tendency to repeatedly choose the same tool for repeated use may have undesired consequences.

Further, an unsuitable condition of a tool may not be evident or even easily determinable except through use and, while it may appear that several interchangeable tools are available, a given tool may not, in fact; be in satisfactory condition or a substituted tool may not provide satisfactory results or results that are complementary to or compatible with other processes within a manufacturing line.

It is not possible, even on identical tools, to exactly maintain all processing parameters unchanged.

For example, astigmatism across the field of a lithographic exposure tool can compromise otherwise identical exposures made in a step-and-repeat fashion.

Such variation in process parameters, even on a single tool, may use a significant portion of the so-called "process window" for a given process and closely matching performance on a different tool is often obtained only with difficulty.

Therefore, while there are advantages in manufacturing yield and product consistency through consistent use of a particular tool, a change of condition of the tool may severely compromise a large segment of a production run if unsuitable operating conditions are not detected in a timely fashion and if one specific tool is used for all devices in a production run, a set of jobs or lots, or an entire manufacturing line since a replacement tool may not, as a practical matter, be available to substitute for another tool taken out of service.

Additionally, the substitution of one tool for another in a production line may carry economic costs such as the time necessary to implement the substitution, change of throughput and the like while the condition of any tool may only be determinable through at least periodic use.

Therefore, significant practical trade-offs exist between consistent use of a particular tool and use of a plurality of tools in sequence or alternation to carry out a process.

However, the number of processes which can be carried out between maintenance operations can be strongly affected by both the nature of the process performed and the process parameter tolerances within the product.

Although resulting variations in product are thus unavoidable, every effort must be made to keep the entire product set from flowing through the tool in question until a final product certification can be completed.

Currently, there is no systematic methodology for relating tool use, process condition change with tool usage pattern and tool maintenance with product requirements.

Moreover, merely alternating or sequencing use of tools in a tool set (e.g. a group of tools suitable to a particular process) is often inconsistent with efficiency and high levels of productivity.

Currently, there is no procedure for preventing an operator from placing an unqualified tool in a manufacturing line.

Therefore, productivity should be of paramount importance and consideration of tool condition or balancing of tool use may be a significant distraction.

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